A. Field of the Invention
The invention relates to current interrupters, and comprises a current interrupter providing an indication at a remote monitoring station of an interruption of current flow through the interrupter.
B. Prior Art
Current interrupters are commonly used in electric power systems to interrupt current flow through power lines on the occurrence of fault conditions. In large power systems, the interrupters may carry currents of hundreds or even thousands of amperes, at potentials of thousands of volts.
A variety of current interrupters are currently in use. Thermal current interrupters are commonly used at low current and voltage levels and where only a moderate response time is required. Mechanical interrupters are frequently used where high voltages and currents are carried, and where fast response time is required. Mechanical interrupters physically separate portions of the current path by means such as movement of a piston in response to gas pressure or to other force-applying means such as electromagnets and the like. Recently, explosively-actuated current interrupters have found increasing use in high voltage, high current fast response time applications. These interrupters physically sever the current path by explosive charges.
Current interrupters frequently operate in a hostile environment. In many applications, they are located out of doors and often are not sheltered from the environment. Thus, they are subject to extremes of temperature, moisture, and other such environmental conditions which create a hostile environment for electronic circuitry. Further, they are subject to electromagnetic radiation fields of high intensity, and thus operate in an inherently "noisy" electric environment.
Numerous different types of condition sensors have been used to monitor the status of current flow through interrupters and to provide an indication of the status of current flow to a remote monitor station. Such systems typically have relied on a variety of sensors which monitor such physical parameters as electrical continuity, temperature, pressure, etc., within the interrupter. Signals indicative of these quantities have then been transmitted back to the remote monitor station, typically over standard electric cabling. Because of the hostile environment in which they must operate, significant precautions must be taken to design and construct the sensor so as to insure reliable operation over the range of operating conditions to which it will be subjected. This is particularly true with respect to such parameters as temperature, which seriously degrade operation of electronic circuitry, as well as with respect to noise pick-up in the high-field environment in which the sensor must be located. Thus, reliable sensors are significantly expensive, and add substantially to the cost of the current interrupter.